The usage of, and demand for, mobile telecommunications continue to increase at a staggering rate. Wireless telecommunications service providers are constantly seeking new ways to improve and expand the services they provide while lowering their investment and operational costs. This ever-increasing demand has driven the development of new and improved topologies and protocols for wireless communications systems. It is now possible to route voice communications, in packetized form, over Internet Protocol (IP) systems conventionally associated with computer data communications. Such capabilities hold the promise increasing efficiency and decreasing costs associated with wireless communications.
Interest grows in IP-based communications as an alternative to conventional circuit switched systems. Circuit switched systems require dedicated channels, reserving an ISUP (ISDN user part) link for any given communication. Therefore, any given call effectively monopolizes a line (e.g. trunk or E1/T1 line) between call origin and destination; requiring a separate line for each call processed. Even in conventional “wireless” communications systems, a call is generally only wireless between the mobile unit and its closest base station, which thereafter typically routes the call on circuit switched infrastructure. For example, in a typical GSM (Global System for Mobile communications) network, once a signal is received at the base station, it is thereafter routed via circuit switched infrastructure to the mobile switching center (MSC) and the rest of the GSM system.
It should thus easily be appreciated that as demand continues to increase, infrastructure associated with circuit switched systems must increase correspondingly. This results in increased system overhead, reduced call volume bandwidth, and increased user costs to cover the additional overhead.
In comparison, IP communications packetize voice data for transmission over existing IP networks; enabling users to communicate (e.g. via phone calls or computer-based conferencing applications) as long as they want for only the cost of the access to the IP network. IP infrastructure is ubiquitous; and use of IP infrastructure is not dedicated (i.e. multiple users utilize, one packet at a time, the same resources), lowering system overhead and use costs.
Although IP network communication is, in some respects, advantageous over circuit switched communication, other considerations limit the commercial usefulness of conventional IP network implementations. Consider, for example, a wireless communications system where communications between two disparate radio access networks are transferred across and IP based network.
Usually, each radio access network will interact with a media gateway in the IP network that serves as an interface to the IP network. Conventionally in such topologies there is no protocol or capability for direct address information exchange between the media gateways on a per-call basis. This usually results in superfluous exchanges between other wireless infrastructure (e.g., ATM based transfers between MSCs) that degrade the efficiency and quality of communication.